The invention relates to an axial fan for a computer. It further relates to a cooling apparatus for an integrated circuit, a cooling apparatus for a microprocessor, a power supply unit for a computer and a case for a computer, each comprising such an axial fan.
Axial fans or axial ventilators of this kind are used for cooling computers and computer components. At axial fans primarily an airflow in the direction of the rotation axis of the fan is generated. This in contrast to radial fans at which the air is drawn in axially, but is then accelerated primarily in radial direction, partially using centrifugal forces and is, depending on the specific embodiment, blown off directly or redirected. There are different places of installation for axial fans in computers. For cooling of single components the fan is for example arranged directly above the specific component. Usually the cooling of components is done using a heatsink. This is attached to the component. The fan causes indirectly, across the heatsink, with its airflow a cooling of the component. At computers typically the CPU, i.e. the central processor, is cooled in this way. A further typical place of installation is the wall of the case of computers. In this kind of arrangement, axial fans are mostly used such that they draw in hot air from the inside of the case and blow it off to the outside. Thereby, colder ambient air flows through chinks and openings to the inside of the case. However, it is also possible, in a reverse manner, to use an axial fan such that it draws in ambient air and blows it into the inside of the case. A very widely used variant of cooling of computers is to arrange a fan such that warm air is drawn from the inside of the case through the power supply unit and blown off to the outside. An important feature of axial fans designed for the field of application “computer” are precisely defined maximum outer dimensions or installation dimensions, which are adjusted to the standards and specifications of the particular cases, power supply units, boards and/or processors.
The known axial fans for computers are usually loud and often cause especially disturbing noises, in particular a buzzing noise at rotational frequencies above 2000 rotations per minute. A known measure for reduction of these noises is a thermo-regulation of the rotational frequency of the fan. This is, however, only effective if the temperature of the device actually allows a reduction of the effect of the fan. A further known measure is the installation of multiple fans. These can then be operated, at an overall equal ventilation effect, each with a lower rotational frequency than a single fan, which altogether results in lower noise emissions. These known measures are, however, because of the additionally needed components, mostly expensive and also imperfect concerning their effectiveness. Further developments are based on designing the fan blades in a special way which, however, led only to moderate improvement results.